Route line color customization

We've added a new Route color selection panel, allowing users to apply a custom color palette to the route lines and stop pins representing any generated routes. New routes will be generated using EasyRoutes' default set of route line/pin colors; users can update the route line/pin colors for any existing route from the same modal used to edit the name of the route (shown above), by either inputting a custom color hex code, or clicking the existing color tile and selecting a new color from the palette that appears.